This application claims priority to EP/01120992.1 filed Aug. 31, 2001 under the European Patent Convention and which is incorporated by reference herein in its entirety.
The invention relates to a combustion-chamber arrangement for gas turbines, having an annular combustion chamber connected to at least one burner and leading into a turbine space, an annular-combustion-chamber wall which defines the annular combustion chamber being of double-shell construction, and an inner shell of the annular-combustion-chamber wall being composed of lining elements releasably arranged on an outer shell of the annular-combustion-chamber wall, and a gap space through which a cooling medium can flow being formed between the inner shell and the outer shell of the annular-combustion-chamber wall. The invention also relates to a gas turbine having such a combustion-chamber arrangement.
In principle, various concepts of combustion-chamber arrangements are known for gas turbines. Thus, gas turbines are known in the prior art which have combustion-chamber arrangements which are composed of a multiplicity of individual combustion chambers which open into a common annular gap. The annular gap at the same time constitutes a transition to the turbine space, in which the moving blades and the guide blades of the gas turbine are arranged. During the combustion of a mixture ignited by burners connected upstream of the individual combustion chambers, this mixture consisting of an oxygen-containing fuel gas and a propellant, hot gases which are produced propagate through the individual combustion chambers in the direction of the annular gap and enter the turbine space via the latter in order to drive the moving blades of the turbine there. Another concept of a combustion-chamber arrangement provides for a single annular combustion chamber instead of a multiplicity of individual combustion chambers. Fuel-gas/propellant mixture ignited in burners enters such an annular combustion chamber, continues to burn therein and expands in the direction of a turbine space connected downstream of the annular combustion chamber. The invention relates to a combustion-chamber arrangement which uses the last-mentioned construction, that is to say an annular combustion chamber.
Since the walls of the annular combustion chamber are subjected to high thermal loads on account of the combustion taking place in the interior of the annular combustion chamber, these parts of the gas turbine must be efficiently cooled. To this end, it is known to provide double-shell walls in such annular combustion chambers, an outer shell being arranged on which an inner shell composed of individual lining elements is arranged. Provided in this case between the outer shell and the inner shell is a gap space, through which a cooling medium is directed, the cooling medium convectively cooling the inner shell of the annular combustion chamber.
In order to design the inner shell of the annular-combustion-chamber wall so as to be interchangeable, this inner shell is composed of lining elements releasably connected to the outer shell of the annular-combustion-chamber wall. To this end, rail-like rods are arranged on the outer shell in annular combustion chambers known from the prior art, and hooks arranged on the lining elements are pushed over said rods in order to suspend the lining elements. The lining elements must be pushed over the entire length of the rail-like rods, which requires a correspondingly long space for fitting and removing the lining elements. In this case, the rail-like rods are arranged in the direction of the axial extent of the annular combustion chamber, so that a corresponding fitting space is required in this direction for fitting and removing the lining elements.
The rail-like rods of the annular combustion chambers known from the prior art have a length of about half a meter, so that there must be a fitting space having a length of at least half a meter in the axial direction of the combustion chamber in the direction of flow upstream of or downstream of the end of the rail-like rods. However, as viewed in the direction of flow, the turbine blades are arranged directly downstream of the combustion chamber, and the burner is arranged directly upstream of the combustion chamber, so that sufficient space for fitting or removing the lining elements remains neither upstream of nor downstream of the rail-like rods.
Therefore complicated dismantling of the gas turbine must be effected for fitting or removing the lining elements. Thus, for example, the outer casing must be taken off or the rotor must be additionally removed, which means a great deal of additional work for the exchange of the lining elements. In this respect, there is a considerable demand for a simplification in the construction of such a combustion-chamber arrangement.
Based on the prior art, the object of the invention is therefore to develop a combustion-chamber arrangement of the type mentioned at the beginning to the effect that it is possible to exchange individual lining elements of the inner shell of the annular-combustion-chamber wall with comparatively little outlay.
To achieve this object, it is proposed with the invention that the lining elements be of trapezoidal design having in each case a fastening structure, formed in each of the longitudinal sides, for releasably fastening to a corresponding mating structure of an adjoining lining element and/or a supporting structure connected to the outer shell.
Due to the trapezoidal design of the lining elements, i.e. the side edges, running at an angle to the end faces which differs from 90xc2x0, of the lining elements and also the fastening structures formed laterally on each of the longitudinal sides and directed outward, a slight displacement is sufficient in order to release and remove the trapezoidal lining element from the corresponding mating structures. The other way round, the lining element can be inserted and fastened to the mating structures by means of a slight displacement. In an exemplary embodiment, the axial displacement required for fitting or removing the lining element is only 0.1 to 0.05 meters, which is a marked reduction in the length of the required space compared with the 0.5 meters known from the prior art. Thus the gas turbine need not be further dismantled for fitting or removing the lining elements in a combustion-chamber arrangement according to the invention. Nor is it necessary to remove the outer casing or the rotor.
According to an advantageous development of the invention, grooves or tongues are proposed as fastening structure and mating structure, respectively. In this case, the grooves may be arranged as fastening structure on the longitudinal sides of the lining elements of trapezoidal design, and the tongues may be arranged as mating structure on an adjoining lining element or on the supporting structure connected to the outer shell. Conversely, it is likewise conceivable for the trapezoidal lining element to have a tongue on its longitudinal side, this tongue engaging in a longitudinal groove formed on an adjoining lining element or on a supporting structure connected to the outer shell.
For removal, a lining element arranged in the composite of the inner shell is displaced in the direction of its wider end face, in the course of which the groove can be released from the tongue on account of the trapezoidal design of the lining element, and the lining element can be removed from the complete structure.
A supporting structure connected to the outer shell of the annular-combustion-chamber arrangement is in each case expediently located between the individual lining elements, at least along their longitudinal sides. This prevents the inner shell of the annular-combustion-chamber wall from becoming unstable when an individual lining element is released.
Fitting or removal of the lining elements is further facilitated if they do not extend over the entire axial length of the annular combustion chamber but only cover part of this length, at least two lining elements being arranged one behind the other for the complete lining of the annular combustion chamber in the axial direction. By such a measure, the individual lining elements are kept small and are thus simpler to manipulate.
According to a further advantageous development of the invention, the annular combustion chamber, in its axial extent, is set at an angle to a machine axis defined by the axial extent of the turbine space or the turbine shaft. Such an angled arrangement results in a decreasing diameter of the annular combustion chamber in the direction of the turbine space, as a result of which an axial subdivision of the inner shell of the annular-combustion-chamber wall inevitably leads to trapezoidal segments. Thus trapezoidal lining elements may be used which are all arranged so as to be oriented with their narrower end edge in the direction of the turbine space and with their wider end edge in the direction of the burner.
If the annular combustion chamber, as proposed according to a further advantageous development of the invention, is repeatedly arranged at an angle to the machine axis in different steps, the lining elements in each case extending over an area lying between two angling edges, the trapezoidal lining elements can be kept smaller and so as to be simpler to handle and thus their fitting and removal is facilitated.
To fix the lining elements, it is proposed according to a further advantageous development of the invention that the lining elements in each case have additional fastening structures. Such a fastening structure may be, for example, a fastening opening for a fixing element to be passed through, such as a screw bolt for example. In this case, it is preferred that the fastening opening is arranged on a narrower base side of the trapezoidal lining element. As a further possibility of additionally securing the lining element, a longitudinal groove may be provided on a side opposite the narrower front side. This longitudinal groove may likewise be fastened with a screw bolt. These bolts constitute the only fixed points of the construction, the first in two directions and the second in one direction.
Furthermore, a gas turbine which has a combustion-chamber arrangement with one or more of the features described above is proposed with the invention. According to an advantageous development of the gas turbine, it has an axially displaceable burner insert. By axial displaceability of the burner insert, adequate space can be created for displacing the trapezoidal lining elements. For fitting or removing, the axially displaceable burner insert is simply displaced axially in a direction away from the combustion-chamber wall, and the intermediate space thus produced between burner and combustion-chamber arrangement can be utilized in order to axially displace the trapezoidal lining elements during the fitting or removal.